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Lopes JC, Veiga VP, Seminiuk B, Santos LOF, Luiz AMC, Fernandes CA, Kinasz CT, Pellizari VH, Duarte RTD. Freezing and thawing in Antarctica: characterization of antifreeze protein (AFP) producing microorganisms isolated from King George Island, Antarctica. Braz J Microbiol 2024; 55:1451-1463. [PMID: 38656427 PMCID: PMC11153389 DOI: 10.1007/s42770-024-01345-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 04/12/2024] [Indexed: 04/26/2024] Open
Abstract
Antarctic temperature variations and long periods of freezing shaped the evolution of microorganisms with unique survival mechanisms. These resilient organisms exhibit several adaptations for life in extreme cold. In such ecosystems, microorganisms endure the absence of liquid water and exhibit resistance to freezing by producing water-binding molecules such as antifreeze proteins (AFP). AFPs modify the ice structure, lower the freezing point, and inhibit recrystallization. The objective of this study was to select and identify microorganisms isolated from different Antarctic ecosystems based on their resistance to temperatures below 0 °C. Furthermore, the study sought to characterize these microorganisms regarding their potential antifreeze adaptive mechanisms. Samples of soil, moss, permafrost, and marine sediment were collected on King George Island, located in the South Shetland archipelago, Antarctica. Bacteria and yeasts were isolated and subjected to freezing-resistance and ice recrystallization inhibition (IR) tests. A total of 215 microorganisms were isolated, out of which 118 were molecularly identified through molecular analysis using the 16S rRNA and ITS regions. Furthermore, our study identified 24 freezing-resistant isolates, including two yeasts and 22 bacteria. A total of 131 protein extracts were subjected to the IR test, revealing 14 isolates positive for AFP production. Finally, four isolates showed both freeze-resistance and IR activity (Arthrobacter sp. BGS04, Pseudomonas sp. BGS05, Cryobacterium sp. P64, and Acinetobacter sp. M1_25C). This study emphasizes the diversity of Antarctic microorganisms with the ability to tolerate freezing conditions. These microorganisms warrant further investigation to conduct a comprehensive analysis of their antifreeze capabilities, with the goal of exploring their potential for future biotechnological applications.
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Affiliation(s)
- J C Lopes
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
- Postgraduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - V P Veiga
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
| | - B Seminiuk
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
| | - L O F Santos
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
| | - A M C Luiz
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
- Postgraduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - C A Fernandes
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
| | - C T Kinasz
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil
- Postgraduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, Florianópolis, Brazil
| | - V H Pellizari
- Oceanographic Institute, Department of Biological Oceanography, University of São Paulo, 05508-120, São Paulo, SP, Brazil
| | - R T D Duarte
- Laboratory of Molecular Ecology and Extremophiles, Department of Microbiology, Immunology and Parasitology, Federal University of Santa Catarina, Campus Reitor João David Ferreira Lima, s/n Trindade, 88040-900, Florianópolis, SC, Brazil.
- Postgraduate Program in Biotechnology and Biosciences, Federal University of Santa Catarina, Florianópolis, Brazil.
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Arakawa K, Yanai J, Watanabe K. Study of the Ca2+-dependent gene expression of EuPrt, an extracellular metalloprotease produced by the psychro-tolerant bacterium Exiguobacterium undae Su-1. Biosci Biotechnol Biochem 2022; 86:1308-1317. [PMID: 35776951 DOI: 10.1093/bbb/zbac109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 05/31/2022] [Indexed: 11/14/2022]
Abstract
The effect of a Ca2+ ion on the gene expression of an on-demand type of metalloprotease from psychrotrophic Exiguobacterium undae Su-1 (EuPrt) was studied. We first established a modified mM9 medium for strain Su-1 to examine its effect in more detail. Then, when the strain was cultured in mM9 medium and 1.0 mM CaCl2 was added, we detected the mature EuPrt and its precursor proteins via Western blotting analysis and found the relative protease activity and its transcription increased by 50-fold and 7-fold, respectively, at the peak. Furthermore, the intracellular concentration of Ca2+ ions was analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-AES) with other metal ions along the growth of strain Su-1. The intracellular concentration of Ca2+ ion was found to increase as much as 3-fold in response to the addition of an extracellular Ca2+ ions, indicating that euPrt gene expression is regulated by sensing its intracellular concentration.
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Affiliation(s)
- Kiyoaki Arakawa
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo, Sakyo, Kyoto, Japan
| | - Junta Yanai
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo, Sakyo, Kyoto, Japan
| | - Kunihiko Watanabe
- Division of Applied Life Sciences, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo, Sakyo, Kyoto, Japan
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3
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Dimov SG. The unusual microbiota of the traditional Bulgarian dairy product Krokmach – A pilot metagenomics study. INT J DAIRY TECHNOL 2021. [DOI: 10.1111/1471-0307.12809] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Svetoslav G Dimov
- Department of Genetics Faculty of Biology Sofia University “St. Kliment Ohridski” 8, Dragan Tzankov blvd. Sofia 1164 Bulgaria
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4
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Abramov A, Vishnivetskaya T, Rivkina E. Are permafrost microorganisms as old as permafrost? FEMS Microbiol Ecol 2021; 97:6143815. [PMID: 33601419 DOI: 10.1093/femsec/fiaa260] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 12/23/2020] [Indexed: 11/13/2022] Open
Abstract
Permafrost describes the condition of earth material (sand, ground, organic matter, etc.) cemented by ice when its temperature remains at or below 0°C continuously for longer than 2 years. Evidently, permafrost is as old as the time passed from freezing of the earth material. Permafrost is a unique phenomenon and may preserve life forms it encloses. Therefore, in order to talk confidently about the preservation of paleo-objects in permafrost, knowledge about the geological age of sediments, i.e. when the sediments were formed, and permafrost age, when those sediments became permanently frozen, is essential. There are two types of permafrost-syngenetic and epigenetic. The age of syngenetic permafrost corresponds to the geological age of its sediments, whereas the age of epigenetic permafrost is less than the geological age of its sediments. Both of these formations preserve microorganisms and their metabolic products; however, the interpretations of the microbiological and molecular-biological data are inconsistent. This paper reviews the current knowledge of time-temperature history and age of permafrost in relation to available microbiological and metagenomic data.
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Affiliation(s)
- Andrey Abramov
- Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino 142290, Russia
| | - Tatiana Vishnivetskaya
- Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino 142290, Russia.,University of Tennessee, Center for Environmental Biotechnology, Knoxville, TN 37996, USA
| | - Elizaveta Rivkina
- Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, Pushchino 142290, Russia
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5
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Castro-Severyn J, Pardo-Esté C, Mendez KN, Morales N, Marquez SL, Molina F, Remonsellez F, Castro-Nallar E, Saavedra CP. Genomic Variation and Arsenic Tolerance Emerged as Niche Specific Adaptations by Different Exiguobacterium Strains Isolated From the Extreme Salar de Huasco Environment in Chilean - Altiplano. Front Microbiol 2020; 11:1632. [PMID: 32760381 PMCID: PMC7374977 DOI: 10.3389/fmicb.2020.01632] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/23/2020] [Indexed: 12/17/2022] Open
Abstract
Polyextremophilic bacteria can thrive in environments with multiple stressors such as the Salar de Huasco (SH). Microbial communities in SH are exposed to low atmospheric pressure, high UV radiation, wide temperature ranges, salinity gradient and the presence of toxic compounds such as arsenic (As). In this work we focus on arsenic stress as one of the main adverse factors in SH and bacteria that belong to the Exiguobacterium genus due to their plasticity and ubiquity. Therefore, our aim was to shed light on the effect of niche conditions pressure (particularly arsenic), on the adaptation and divergence (at genotypic and phenotypic levels) of Exiguobacterium strains from five different SH sites. Also, to capture greater diversity in this genus, we use as outgroup five As(III) sensitive strains isolated from Easter Island (Chile) and The Great Salt Lake (United States). For this, samples were obtained from five different SH sites under an arsenic gradient (9 to 321 mg/kg: sediment) and isolated and sequenced the genomes of 14 Exiguobacterium strains, which had different arsenic tolerance levels. Then, we used comparative genomic analysis to assess the genomic divergence of these strains and their association with phenotypic differences such as arsenic tolerance levels and the ability to resist poly-stress. Phylogenetic analysis showed that SH strains share a common ancestor. Consequently, populations were separated and structured in different SH microenvironments, giving rise to multiple coexisting lineages. Hence, this genotypic variability is also evidenced by the COG (Clusters of Orthologous Groups) composition and the size of their accessory genomes. Interestingly, these observations correlate with physiological traits such as growth patterns, gene expression, and enzyme activity related to arsenic response and/or tolerance. Therefore, Exiguobacterium strains from SH are adapted to physiologically overcome the contrasting environmental conditions, like the arsenic present in their habitat.
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Affiliation(s)
- Juan Castro-Severyn
- Laboratorio de Microbiología Aplicada y Extremófilos, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile.,Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Katterinne N Mendez
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Naiyulin Morales
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Sebastián L Marquez
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Franck Molina
- Sys2Diag CNRS/Alcediag, CNRS UMR 3145, Montpellier, France
| | - Francisco Remonsellez
- Laboratorio de Microbiología Aplicada y Extremófilos, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile.,Centro de Investigación Tecnológica del Agua en el Desierto-CEITSAZA, Universidad Católica del Norte, Antofagasta, Chile
| | - Eduardo Castro-Nallar
- Center for Bioinformatics and Integrative Biology, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Claudia P Saavedra
- Laboratorio de Microbiología Molecular, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
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Orizola J, Ríos-Silva M, Muñoz-Villagrán C, Vargas E, Vásquez C, Arenas F. In vitro biosynthesis of Ag, Au and Te-containing nanostructures by Exiguobacterium cell-free extracts. BMC Biotechnol 2020; 20:29. [PMID: 32471409 PMCID: PMC7260758 DOI: 10.1186/s12896-020-00625-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 05/21/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND The bacterial genus Exiguobacterium includes several species that inhabit environments with a wide range of temperature, salinity, and pH. This is why the microorganisms from this genus are known generically as polyextremophiles. Several environmental isolates have been explored and characterized for enzyme production as well as for bioremediation purposes. In this line, toxic metal(loid) reduction by these microorganisms represents an approach to decontaminate soluble metal ions via their transformation into less toxic, insoluble derivatives. Microbial-mediated metal(loid) reduction frequently results in the synthesis of nanoscale structures-nanostructures (NS) -. Thus, microorganisms could be used as an ecofriendly way to get NS. RESULTS We analyzed the tolerance of Exiguobacterium acetylicum MF03, E. aurantiacum MF06, and E. profundum MF08 to Silver (I), gold (III), and tellurium (IV) compounds. Specifically, we explored the ability of cell-free extracts from these bacteria to reduce these toxicants and synthesize NS in vitro, both in the presence or absence of oxygen. All isolates exhibited higher tolerance to these toxicants in anaerobiosis. While in the absence of oxygen they showed high tellurite- and silver-reducing activity at pH 9.0, whereas AuCl4- which was reduced at pH 7.0 in both conditions. Given these results, cell-free extracts were used to synthesize NS containing silver, gold or tellurium, characterizing their size, morphology and chemical composition. Silver and tellurium NS exhibited smaller size under anaerobiosis and their morphology was circular (silver NS), starred (tellurium NS) or amorphous (gold NS). CONCLUSIONS This nanostructure-synthesizing ability makes these isolates interesting candidates to get NS with biotechnological potential.
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Affiliation(s)
- Javier Orizola
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Mirtha Ríos-Silva
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.,Departamento de Ciencias Nucleares, Comisión Chilena de Energía Nuclear, Santiago, Chile
| | - Claudia Muñoz-Villagrán
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Esteban Vargas
- Center for the Development of Nanoscience and Nanotechnology, Santiago, Chile
| | - Claudio Vásquez
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Felipe Arenas
- Laboratorio Microbiología Molecular, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile.
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Wang Y, He L, Xing Y, Zhou W, Pian R, Yang F, Chen X, Zhang Q. Bacterial diversity and fermentation quality of Moringa oleifera leaves silage prepared with lactic acid bacteria inoculants and stored at different temperatures. BIORESOURCE TECHNOLOGY 2019; 284:349-358. [PMID: 30954903 DOI: 10.1016/j.biortech.2019.03.139] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/27/2019] [Accepted: 03/28/2019] [Indexed: 06/09/2023]
Abstract
Four lactic acid bacteria strains (LP, LF, LL, W), isolated and selected from Moringa oleifera leaves (MOL) silage, were identified as Lactobacillus plantarum, L. farciminis, Lactococcus lactis, Weissella thailandensis, respectively. Fermentation quality and bacterial community of MOL ensiled without or with the four strains at 15 °C and 30 °C were investigated. Results showed that all the LAB strains decreased (P < 0.05) the pH and ammonia-N content of MOL silage. Silage stored at 30 °C showed higher (P < 0.05) DM loss, acetic acid and ammonia-N content, and lower LAB count than 15 °C. The environmental temperature also made a great influence on bacterial community of MOL silage. Bacterial diversity was lower and the abundance of Lactobacillus was higher in silages stored at 15 °C. In conclusion, LAB inoculants and a relatively low environmental temperature could be effective to improve the quality of MOL silage.
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Affiliation(s)
- Yi Wang
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
| | - Liwen He
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
| | - Yaqi Xing
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
| | - Wei Zhou
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
| | - Ruiqi Pian
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
| | - Fuyu Yang
- College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Xiaoyang Chen
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China
| | - Qing Zhang
- College of Forestry and Landscape Architecture, Guangdong Province Research Center of Woody Forage Engineering Technology, Guangdong Research and Development Centre of Modern Agriculture (Woody forage) Industrial Technology, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China.
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Cheng D, Tian Z, Feng L, Xu L, Wang H. Diversity analysis of the rhizospheric and endophytic bacterial communities of Senecio vulgaris L. (Asteraceae) in an invasive range. PeerJ 2019; 6:e6162. [PMID: 30643678 PMCID: PMC6327885 DOI: 10.7717/peerj.6162] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 11/25/2018] [Indexed: 11/20/2022] Open
Abstract
Increasing evidence has confirmed the importance of plant-associated bacteria for plant growth and productivity, and thus it is hypothesized that interactions between bacteria and alien plants might play an important role in plant invasions. However, the diversity of the bacterial communities associated with invasive plants is poorly understood. We therefore investigated the diversity of rhizospheric and endophytic bacteria associated with the invasive annual plant Senecio vulgaris L. (Asteraceae) based on 16S rRNA gene data obtained from 57 samples of four Senecio vulgaris populations in a subtropical mountainous area in central China. Significant differences in diversity were observed between plant compartments. Specifically, the rhizosphere harbored many more bacterial operational taxonomic units and showed higher alpha diversity than the leaf and root endospheres. The relative abundance profiles of the bacterial community composition differed substantially between the compartments and populations, especially at the phylum and family levels. However, the top five phyla (Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria, and Acidobacteria) accounted for more than 90% of all the bacterial communities. Moreover, similar endophytic communities with a shared core set of bacteria were observed from different Senecio vulgaris populations. Heavy-metal-resistant, phosphate-solubilizing bacteria (Brevundimonas diminuta), nitrogen-fixing bacteria (Rhizobium leguminosarum), and cold-resistant bacteria (Exiguobacterium sibiricum) were present in the endosphere at relatively high abundance. This study, which reveals the structure of bacterial communities and their putative function in invasive Senecio vulgaris plants, is the first step in investigating the role of plant-bacteria interactions in the invasion of this species in China.
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Affiliation(s)
- Dandan Cheng
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan, China
| | - Zhongsai Tian
- School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China
| | - Liang Feng
- School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China
| | - Lin Xu
- School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan, China
| | - Hongmei Wang
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (Wuhan), Wuhan, China
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9
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Remonsellez F, Castro-Severyn J, Pardo-Esté C, Aguilar P, Fortt J, Salinas C, Barahona S, León J, Fuentes B, Areche C, Hernández KL, Aguayo D, Saavedra CP. Characterization and Salt Response in Recurrent Halotolerant Exiguobacterium sp. SH31 Isolated From Sediments of Salar de Huasco, Chilean Altiplano. Front Microbiol 2018; 9:2228. [PMID: 30294311 PMCID: PMC6158405 DOI: 10.3389/fmicb.2018.02228] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/31/2018] [Indexed: 12/22/2022] Open
Abstract
Poly-extremophiles microorganisms have the capacity to inhabit hostile environments and can survive several adverse conditions that include as variations in temperature, pH, and salinity, high levels UV light and atmospheric pressure, and even the presence of toxic compounds and the formation of reactive oxygen species (ROS). A halotolerant Exiguobacterium strain was isolated from Salar de Huasco (Chilean Altiplano), a well-known shallow lake area with variable salinity levels, little human intervention, and extreme environmental conditions, which makes it ideal for the study of resistant mechanisms and the evolution of adaptations. This bacterial genus has not been extensively studied, although its cosmopolitan location indicates that it has high levels of plasticity and adaptive capacity. However, to date, there are no studies regarding the tolerance and resistance to salinity and osmotic pressure. We set out to characterize the Exiguobacterium sp. SH31 strain and describe its phenotypical and genotypical response to osmotic stress. In this context, as a first step to characterize the response to the SH31 strain to salinity and to establish the bases for a molecular study, we proposed to compare its response under three salt conditions (0, 25, and 50 g/l NaCl). Using different physiology, genomic, and transcriptomic approaches, we determined that the bacterium is able to grow properly in a NaCl concentration of up to 50 g/l; however, the best growth rate was observed at 25 g/l. Although the presence of flagella is not affected by salinity, motility was diminished at 25 g/l NaCl and abolished at 50 g/l. Biofilm formation was induced proportionally with increases in salinity, which was expected. These phenotypic results correlated with the expression of related genes: fliG and fliS Motility); opuBA and putP (transport); glnA, proC, gltA, and gbsA (compatible solutes); ywqC, bdlA, luxS y pgaC (biofilm and stress response); and therefore, we conclude that this strain effectively modifies gene expression and physiology in a differential manner when faced with different concentrations of NaCl and these modifications aid survival.
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Affiliation(s)
- Francisco Remonsellez
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
- Centro de Investigación Tecnológica del Agua en el Desierto (CEITSAZA), Universidad Católica del Norte, Antofagasta, Chile
| | - Juan Castro-Severyn
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Pablo Aguilar
- Lake and Glacier Ecology Research Group, Institute of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Jonathan Fortt
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Cesar Salinas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Sergio Barahona
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Joice León
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Bárbara Fuentes
- Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte, Antofagasta, Chile
| | - Carlos Areche
- Departamento de Química, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Klaudia L. Hernández
- Centro de Investigación Marina Quintay, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Valdivia, Chile
| | - Daniel Aguayo
- Center for Bioinformatics and Integrative Biology, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
| | - Claudia P. Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Santiago, Chile
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Bacterial diversity of artisanal cheese from the Amazonian region of Brazil during the dry and rainy seasons. Food Res Int 2018; 108:295-300. [PMID: 29735061 DOI: 10.1016/j.foodres.2018.03.060] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/18/2018] [Accepted: 03/21/2018] [Indexed: 11/22/2022]
Abstract
The microbiota from artisanal cheeses produced in the Amazonian region is evaluated. Samples of artisanal cheeses were obtained from markets in Conceição do Araguaia and Redenção (Pará, Brazil) over rainy and dry seasons, and their biodiversity was assessed by culture-dependent and culture-independent methods. Mean counts of lactic acid bacteria (LAB) in cheeses ranged from 7.32 to 8.84 log CFU/g, for both seasons. Members of genera Lactobacillus, Lactococcus, Weissella, Enterococcus, Pediococcus, and Leuconostoc were predominant. The amplification of the 16S rRNA V6-V9 region, followed by a temporal temperature-gradient gel electrophoresis (TTGE) and sequencing of the TTGE bands revealed important differences in the microbial composition variability between samples from the two seasons and among cheese samples analyzed. TTGE showed the presence of microorganisms that are frequently found in cheese, such as L. lactis subsp. lactis, as well as other non-usual species, such as Macrococcus caseolyticus and Corynebacterium variabile. Moreover, TTGE analysis revealed the presence of microorganisms that have been isolated from other types of foods (Paralactobacillus selangorenses) along with some not usually found in foods, such as Exiguobacterium acetylicum, plus the presence of pathogenic microorganisms (Granulicatella elegans and Aerococcus sanguinicola). The present molecular approaches combined with culture-dependent methods provided a more detailed description of the microbial ecology of traditional cheeses from the Amazonian region in northern Brazil.
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11
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Castro-Severyn J, Remonsellez F, Valenzuela SL, Salinas C, Fortt J, Aguilar P, Pardo-Esté C, Dorador C, Quatrini R, Molina F, Aguayo D, Castro-Nallar E, Saavedra CP. Comparative Genomics Analysis of a New Exiguobacterium Strain from Salar de Huasco Reveals a Repertoire of Stress-Related Genes and Arsenic Resistance. Front Microbiol 2017; 8:456. [PMID: 28377753 PMCID: PMC5360010 DOI: 10.3389/fmicb.2017.00456] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 03/06/2017] [Indexed: 11/13/2022] Open
Abstract
The Atacama Desert hosts diverse ecosystems including salt flats and shallow Andean lakes. Several heavy metals are found in the Atacama Desert, and microorganisms growing in this environment show varying levels of resistance/tolerance to copper, tellurium, and arsenic, among others. Herein, we report the genome sequence and comparative genomic analysis of a new Exiguobacterium strain, sp. SH31, isolated from an altiplanic shallow athalassohaline lake. Exiguobacterium sp. SH31 belongs to the phylogenetic Group II and its closest relative is Exiguobacterium sp. S17, isolated from the Argentinian Altiplano (95% average nucleotide identity). Strain SH31 encodes a wide repertoire of proteins required for cadmium, copper, mercury, tellurium, chromium, and arsenic resistance. Of the 34 Exiguobacterium genomes that were inspected, only isolates SH31 and S17 encode the arsenic efflux pump Acr3. Strain SH31 was able to grow in up to 10 mM arsenite and 100 mM arsenate, indicating that it is arsenic resistant. Further, expression of the ars operon and acr3 was strongly induced in response to both toxics, suggesting that the arsenic efflux pump Acr3 mediates arsenic resistance in Exiguobacterium sp. SH31.
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Affiliation(s)
- Juan Castro-Severyn
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres BelloSantiago, Chile; Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés BelloSantiago, Chile
| | - Francisco Remonsellez
- Laboratorio de Tecnologías de Membranas, Biotecnología y Medio Ambiente, Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte Antofagasta, Chile
| | - Sandro L Valenzuela
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés Bello Santiago, Chile
| | - Cesar Salinas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello Santiago, Chile
| | - Jonathan Fortt
- Laboratorio de Tecnologías de Membranas, Biotecnología y Medio Ambiente, Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del Norte Antofagasta, Chile
| | - Pablo Aguilar
- Laboratorio de Tecnologías de Membranas, Biotecnología y Medio Ambiente, Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias Geológicas, Universidad Católica del NorteAntofagasta, Chile; Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta and Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de AntofagastaAntofagasta, Chile
| | - Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello Santiago, Chile
| | - Cristina Dorador
- Laboratorio de Complejidad Microbiana y Ecología Funcional, Instituto Antofagasta and Departamento de Biotecnología, Facultad de Ciencias del Mar y Recursos Biológicos, Universidad de AntofagastaAntofagasta, Chile; Centre for Biotechnology and BioengineeringAntofagasta, Chile
| | - Raquel Quatrini
- Laboratorio de Ecofisiología Microbiana, Fundación Ciencia and Vida Santiago, Chile
| | | | - Daniel Aguayo
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés BelloSantiago, Chile; Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de ValparaísoValparaíso, Chile
| | - Eduardo Castro-Nallar
- Centro de Bioinformática y Biología Integrativa, Facultad de Ciencias Biológicas, Universidad Andrés Bello Santiago, Chile
| | - Claudia P Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello Santiago, Chile
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Dastager SG, Mawlankar R, Sonalkar VV, Thorat MN, Mual P, Verma A, Krishnamurthi S, Tang SK, Li WJ. Exiguobacterium enclense sp. nov., isolated from sediment. Int J Syst Evol Microbiol 2015; 65:1611-1616. [PMID: 25716950 DOI: 10.1099/ijs.0.000149] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A Gram-stain-positive bacterium, designated strain NIO-1109(T), was isolated from a marine sediment sample from Chorao Island, Goa, India. Phenotypic and chemotaxonomic characteristics and data from phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NIO-1109(T) was related to the genus Exiguobacterium . Strain NIO-1109(T) exhibited >98.0% 16S rRNA gene sequence similarity with respect to Exiguobacterium indicum HHS 31(T) (99.5%) and Exiguobacterium acetylicum NCIMB 9889(T) (99.1%); the type strains of other species showed <98% similarity. Levels of DNA-DNA relatedness between strain NIO-1109(T) and E. acetylicum DSM 20416(T) and E. indicum LMG 23471(T) were less than 70% (33.0 ± 2.0 and 37 ± 3.2%, respectively). Strain NIO-1109(T) also differed from these two closely related species in a number of phenotypic traits. Based on phenotypic, chemotaxonomic and phylogenetic data, strain NIO-1109(T) is considered to represent a novel species of the genus Exiguobacterium , for which the name Exiguobacterium enclense sp. nov. is proposed. The type strain is NIO-1109(T) ( =NCIM 5457(T) =DSM 25128(T) = CCTCC AB 2011124(T)).
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Affiliation(s)
- Syed G Dastager
- NCIM-Resource Center, CSIR-National Chemical Laboratory, Pune-411008, Maharashtra, India
| | - Rahul Mawlankar
- NCIM-Resource Center, CSIR-National Chemical Laboratory, Pune-411008, Maharashtra, India
| | - Vidya V Sonalkar
- NCIM-Resource Center, CSIR-National Chemical Laboratory, Pune-411008, Maharashtra, India
| | - Meghana N Thorat
- NCIM-Resource Center, CSIR-National Chemical Laboratory, Pune-411008, Maharashtra, India
| | - Poonam Mual
- Microbial Type Culture Collection and Gene Bank (MTCC), CSIR-Institute of Microbial Technology, Sector-39A, Chandigarh-160036, India
| | - Ashish Verma
- Microbial Type Culture Collection and Gene Bank (MTCC), CSIR-Institute of Microbial Technology, Sector-39A, Chandigarh-160036, India
| | - Srinivasan Krishnamurthi
- Microbial Type Culture Collection and Gene Bank (MTCC), CSIR-Institute of Microbial Technology, Sector-39A, Chandigarh-160036, India
| | - Shan-Kun Tang
- Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education and Laboratory for Conservation and Utilization of Bio-resources, Yunnan Institute of Microbiology, Yunnan University, Kunming, Yunnan, 650091, PR China
| | - Wen-Jun Li
- Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education and Laboratory for Conservation and Utilization of Bio-resources, Yunnan Institute of Microbiology, Yunnan University, Kunming, Yunnan, 650091, PR China
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Yang J, Wang C, Wu J, Liu L, Zhang G, Feng J. Characterization of a multiresistant mosaic plasmid from a fish farm Sediment Exiguobacterium sp. isolate reveals aggregation of functional clinic-associated antibiotic resistance genes. Appl Environ Microbiol 2014; 80:1482-8. [PMID: 24362420 PMCID: PMC3911065 DOI: 10.1128/aem.03257-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 12/11/2013] [Indexed: 11/20/2022] Open
Abstract
The genus Exiguobacterium can adapt readily to, and survive in, diverse environments. Our study demonstrated that Exiguobacterium sp. strain S3-2, isolated from marine sediment, is resistant to five antibiotics. The plasmid pMC1 in this strain carries seven putative resistance genes. We functionally characterized these resistance genes in Escherichia coli, and genes encoding dihydrofolate reductase and macrolide phosphotransferase were considered novel resistance genes based on their low similarities to known resistance genes. The plasmid G+C content distribution was highly heterogeneous. Only the G+C content of one block, which shared significant similarity with a plasmid from Exiguobacterium arabatum, fit well with the mean G+C content of the host. The remainder of the plasmid was composed of mobile elements with a markedly lower G+C ratio than the host. Interestingly, five mobile elements located on pMC1 showed significant similarities to sequences found in pathogens. Our data provided an example of the link between resistance genes in strains from the environment and the clinic and revealed the aggregation of antibiotic resistance genes in bacteria isolated from fish farms.
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Affiliation(s)
- Jing Yang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Chao Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jinyu Wu
- Institute of Genomic Medicine, Wenzhou Medical College, Wenzhou, Zhejiang, China
| | - Li Liu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Gang Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jie Feng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
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14
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Vijayalaxmi S, Anu Appaiah KA, Jayalakshmi SK, Mulimani VH, Sreeramulu K. Production of bioethanol from fermented sugars of sugarcane bagasse produced by lignocellulolytic enzymes of Exiguobacterium sp. VSG-1. Appl Biochem Biotechnol 2013; 171:246-60. [PMID: 23832861 DOI: 10.1007/s12010-013-0366-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Accepted: 06/23/2013] [Indexed: 11/26/2022]
Abstract
Exiguobacterium sp. VSG-1 was isolated from the soil sample and characterized for the production of lignocellulolytic enzymes. Production of these enzymes by the strain VSG-1 was carried out using steam-exploded sugarcane bagasse (SCB) and found to secrete cellulase, pectinase, mannanase, xylanase, and tannase. The growth and enzyme production were found to be optimum at pH 9.0 and 37 °C. Upon steam explosion of SCB, the cellulose increased by 42 %, whereas hemicelluloses and lignin decreased by 40 and 62 %, respectively. Enzymatic hydrolysis of steam-exploded SCB yielded 640 g/l of total sugars. Fermentation of sugars produced from pretreated SCB was carried out by using Saccharomyces cerevisiae at pH 5.0 and 30 °C. The alcohol produced was calculated and found to be 62.24 g/l corresponding to 78 % of the theoretical yield of ethanol. Hence, the strain VSG-1 has an industrial importance for the production of fermentable sugars for biofuels.
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Affiliation(s)
- S Vijayalaxmi
- Department of Biochemistry, Gulbarga University, Gulbarga, 585106, Karnataka, India
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15
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Complete genome sequence of the Thermophilic Bacterium Exiguobacterium sp. AT1b. J Bacteriol 2011; 193:2880-1. [PMID: 21460088 DOI: 10.1128/jb.00303-11] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here we present the genome of strain Exiguobacterium sp. AT1b, a thermophilic member of the genus Exiguobacterium whose representatives were isolated from various environments along a thermal and physicochemical gradient. This genome was sequenced to be a comparative resource for the study of thermal adaptation with a psychroactive representative of the genus, Exiguobacterium sibiricum strain 255-15, that was previously sequenced by the U.S. Department of Energy's (DOE's) Joint Genome Institute (JGI) (http://genome.ornl.gov/microbial/exig/).
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16
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Azizoglu RO, Kathariou S. Impact of growth temperature and agar versus liquid media on freeze-thaw tolerance of Yersinia enterocolitica. Foodborne Pathog Dis 2010; 7:1125-8. [PMID: 20528173 DOI: 10.1089/fpd.2009.0526] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Yersinia enterocolitica is a foodborne pathogen well known for its ability to grow at low temperatures. Recent studies with another psychrotrophic foodborne pathogen, Listeria monocytogenes, revealed that temperature of growth had pronounced impact on survival following repeated freezing and thawing (cryotolerance). Listerial cryotolerance was significantly more pronounced when bacteria were grown at 37 degrees C than following growth at either 4 degrees C or 25 degrees C. However, it is not known whether such impact of growth temperature is a general adaptation shared with other foodborne pathogens. In this study, we investigated the impact of growth temperature (4 degrees C, 25 degrees C, and 37 degrees C) on cryotolerance of Y. enterocolitica. In strong contrast to findings previously obtained with Listeria spp., cryotolerance of Y. enterocolitica was impaired following growth in liquid media at 37 degrees C, with cell concentration dropping to undetectable levels (<10(1) colony forming unit/mL) following as few as six freeze-thaw cycles. On the other hand, when the bacteria were grown at 4 degrees C, cryotolerance was significantly higher (p < 0.05), and substantial survival was maintained even after 18 cycles (2-5 log reduction, depending on strain). Enhanced cryotolerance was also observed with cultures grown at 25 degrees C. Bacteria grown at 37 degrees C on agar were significantly more cryotolerant than following growth at 37 degrees C in liquid media (p < 0.05). The data suggest species-specific impact of growth temperature and liquid versus agar medium on cryotolerance of cold-tolerant bacteria.
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Affiliation(s)
- Reha Onur Azizoglu
- Department of Food, Bioprocessing, and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina 27695-7624, USA
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17
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Dartnell LR, Hunter SJ, Lovell KV, Coates AJ, Ward JM. Low-temperature ionizing radiation resistance of Deinococcus radiodurans and Antarctic Dry Valley bacteria. ASTROBIOLOGY 2010; 10:717-732. [PMID: 20950171 DOI: 10.1089/ast.2009.0439] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The high flux of cosmic rays onto the unshielded surface of Mars poses a significant hazard to the survival of martian microbial life. Here, we determined the survival responses of several bacterial strains to ionizing radiation exposure while frozen at a low temperature characteristic of the martian near-subsurface. Novel psychrotolerant bacterial strains were isolated from the Antarctic Dry Valleys, an environmental analogue of the martian surface, and identified by 16S rRNA gene phylogeny as representatives of Brevundimonas, Rhodococcus, and Pseudomonas genera. These isolates, in addition to the known radioresistant extremophile Deinococcus radiodurans, were exposed to gamma rays while frozen on dry ice (-79°C). We found D. radiodurans to exhibit far greater radiation resistance when irradiated at -79°C than was observed in similar studies performed at higher temperatures. This greater radiation resistance has important implications for the estimation of potential survival times of microorganisms near the martian surface. Furthermore, the most radiation resistant of these Dry Valley isolates, Brevundimonas sp. MV.7, was found to show 99% 16S rRNA gene similarity to contaminant bacteria discovered in clean rooms at both Kennedy and Johnson Space Centers and so is of prime concern to efforts in the planetary protection of Mars from our lander probes. Results from this experimental irradiation, combined with previous radiation modeling, indicate that Brevundimonas sp. MV.7 emplaced only 30 cm deep in martian dust could survive the cosmic radiation for up to 100,000 years before suffering 10⁶ population reduction.
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Affiliation(s)
- Lewis R Dartnell
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology, University College London, UK
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18
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Stres B, Philippot L, Faganeli J, Tiedje JM. Frequent freeze-thaw cycles yield diminished yet resistant and responsive microbial communities in two temperate soils: a laboratory experiment. FEMS Microbiol Ecol 2010; 74:323-35. [DOI: 10.1111/j.1574-6941.2010.00951.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Azizoglu RO, Kathariou S. Inactivation of a cold-induced putative rna helicase gene of Listeria monocytogenes is accompanied by failure to grow at low temperatures but does not affect freeze-thaw tolerance. J Food Prot 2010; 73:1474-9. [PMID: 20819357 DOI: 10.4315/0362-028x-73.8.1474] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Freeze-thaw tolerance (cryotolerance) of Listeria monocytogenes is markedly influenced by temperature of growth of the bacteria, and may involve responses to low-temperature stresses encountered during freezing and thawing. A cold-sensitive mariner-based transposon mutant of L. monocytogenes F2365 was found to harbor a single insertion in LMOf2365_1746, encoding a putative RNA helicase, and earlier shown by other investigators to be induced during 4 degrees C growth of L. monocytogenes. The mutant had normal growth at 37 degrees C but completely failed to grow at either 4 or 10 degrees C, and had impaired growth and reduced swarming on soft agar at 25 degrees C. However, the mutation had no discernible influence on the ability of the bacteria to tolerate repeated freezing and thawing after growth at either 25 or 37 degrees C. The findings suggest that the transposon insertion in the putative helicase gene, in spite of the severely cold-sensitive phenotype that accompanies it, does not affect the ability of the bacteria to cope with cold-related stresses encountered during repeated freezing and thawing.
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Affiliation(s)
- Reha O Azizoglu
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
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20
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Affiliation(s)
- Michael Y Galperin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
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Segawa T, Takeuchi N, Ushida K, Kanda H, Kohshima S. Altitudinal changes in a bacterial community on Gulkana Glacier in Alaska. Microbes Environ 2010; 25:171-82. [PMID: 21576870 DOI: 10.1264/jsme2.me10119] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To clarify altitudinal changes in the bacterial community on Gulkana Glacier in Alaska, we analyzed bacterial 16S rRNA gene by low-cycle PCR amplification, denaturing gradient gel electrophoresis (DGGE), and culturing in a snowmelt medium at 4°C. Low-cycle PCR-based cloning revealed the presence of 100 bacterial OTUs; however, 41 OTUs were identified only in a single clone, suggesting that their abundance was limited because of difficulty in predominating on the glacier. In contrast, 17 major OTUs accounted for 57-87% of the clone library at each site, suggesting that they accounted for the major part of the bacteria on the glacier. In addition, five of the 17 OTUs were included in the 21 OTUs cultured in the snowmelt medium. Based on the dominant phylotypes and DGGE results, the bacterial community on the glacier could be divided into three types, corresponding to the snow-covered, snow- and ice-covered, and bare-ice areas of the glacier. Our results suggest that a relatively limited number of bacteria predominate and that each phylotype is adapted to a distinct set of conditions on the glacier.
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Affiliation(s)
- Takahiro Segawa
- Transdisciplinary Research Integration Center, 4–3–13 Toranomon, Minato-ku, Tokyo 105–0001, Japan.
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22
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Cryopreservation of marine thraustochytrids (Labyrinthulomycetes). Cryobiology 2009; 59:363-5. [DOI: 10.1016/j.cryobiol.2009.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2009] [Revised: 08/13/2009] [Accepted: 09/04/2009] [Indexed: 11/18/2022]
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Role of growth temperature in freeze-thaw tolerance of Listeria spp. Appl Environ Microbiol 2009; 75:5315-20. [PMID: 19542335 DOI: 10.1128/aem.00458-09] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The food-borne pathogen Listeria monocytogenes can grow in a wide range of temperatures, and several key virulence determinants of the organism are expressed at 37 degrees C but are strongly repressed below 30 degrees C. However, the impact of growth temperature on the ability of the bacteria to tolerate environmental stresses remains poorly understood. In other microorganisms, cold acclimation resulted in enhanced tolerance against freezing and thawing (cryotolerance). In this study, we investigated the impact of growth temperature (4, 25, and 37 degrees C) on the cryotolerance of 14 strains of L. monocytogenes from outbreaks and from food processing plant environments and four strains of nonpathogenic Listeria spp. (L. welshimeri and L. innocua). After growth at different temperatures, cells were frozen at -20 degrees C, and repeated freeze-thaw cycles were applied every 24 h. Pronounced cryotolerance was exhibited by cells grown at 37 degrees C, with a <1-log decrease after 18 cycles of freezing and thawing. In contrast, freeze-thaw tolerance was significantly reduced (P < 0.05) when bacteria were grown at either 4 or 25 degrees C, with log decreases after 18 freeze-thaw cycles ranging from 2 to >4, depending on the strain. These findings suggest that growth at 37 degrees C, a temperature required for expression of virulence determinants of L. monocytogenes, is also required for protection against freeze-thaw stress. The negative impact of growth at low temperature on freeze-thaw stress was unexpected and has not been reported before with this or other psychrotrophic microorganisms.
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Efficient decomposition of shrimp shell waste using Bacillus cereus and Exiguobacterium acetylicum. J Ind Microbiol Biotechnol 2009; 36:1123-6. [PMID: 19471983 DOI: 10.1007/s10295-009-0587-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Accepted: 04/26/2009] [Indexed: 10/20/2022]
Abstract
Two bacterial cultures were isolated and tested for degradation of shrimp shell waste. According to morphological examination, physiological tests, and applied molecular techniques, isolates were identified as Bacillus cereus and Exiguobacterium acetylicum. Both strains were cultivated separately in flasks with 100 mL of shrimp shell waste broth (3% of washed, dried and ground shrimp shell waste in tap water, pH 7.0) at 37 degrees C. At determined periods of time, deproteinization and demineralization of residuals were measured. Fermentation of 3% shell waste with B. cereus indicated 97.1% deproteinization and 95% demineralization. For E. acetylicum, the level of deproteinization and demineralization was 92.8 and 92%, respectively. Protein content was reduced from 18.7 to 5.3% with B. cereus and to 7.3% with E. acetylicum. No additional supplements were used during the fermentation of shell waste. B. cereus strain showed higher efficacy in decomposition of shell waste and was used for large-scale fermentation in 12 L of 10% shrimp shell waste broth. Incubation of bacteria with shell waste during 14 days at 37 degrees C resulted in 78.6% deproteinization and 73% demineralization. High activity of isolated cultures in decomposition of shrimp shell waste suggests broad potential for application of these bacteria in environmentally friendly approaches to chitin extraction from chitin-rich wastes.
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The Exiguobacterium genus: biodiversity and biogeography. Extremophiles 2009; 13:541-55. [DOI: 10.1007/s00792-009-0243-5] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2008] [Accepted: 03/30/2009] [Indexed: 10/20/2022]
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Identification and Characteristics of A Novel Salt-Tolerant Exiguobacterium sp. for Azo Dyes Decolorization. Appl Biochem Biotechnol 2009; 159:728-38. [DOI: 10.1007/s12010-009-8546-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 01/20/2009] [Indexed: 10/21/2022]
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Qiu Y, Vishnivetskaya TA, Lubman DM. Proteomic Insights: Cryoadaptation of Permafrost Bacteria. SOIL BIOLOGY 2008. [DOI: 10.1007/978-3-540-69371-0_12] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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28
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Okeke BC. Bioremoval of hexavalent chromium from water by a salt tolerant bacterium, Exiguobacterium sp. GS1. J Ind Microbiol Biotechnol 2008; 35:1571-9. [DOI: 10.1007/s10295-008-0399-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Accepted: 07/07/2008] [Indexed: 11/29/2022]
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